Windows 7 - No HDMI output

I have been trying for 2 week, to no avail, to connect an external monitor to extend my desktop to my ASUS ET2203 through an HDMI cable to an ASUS VE245HA. My graphics card is an ATI Radeon Mobility 4570.
I have:
updated the drivers and Catalyst Command Center
Changed cables
Attempted to force output, but the only output available i through VGA, and it will not output anything
Reset my whole PC to factory setting just in case
Spent over an hour with tech support, who claims it should simply plug and play.
Screwed with the output resolutions.

Nothing has helped.

When i connect the hdmi cable to the back of the PC, there is no automatic discovery in windows.

Any help would be greatly appreciated. Thanks

have you checked your bios settings?

Try hooking the monitor to the pc with the both the monitor and pc off. With it hooked up, turn on the monitor first then turn on the pc. See if you can get a picture that way.

Tried both options, including updating the Bios, and making sure the monitor is on.

Tried uninstalling and reinstalling audio drivers, still nothing